A manufacturer of an innovative spinal implant approached MSI for help in assessing the implant’s structural integrity. Of concern was not only the ability of the implant to withstand the forces during deployment, but also to withstand the in vivo physiologic loading.
The longevity of a total hip arthroplasty depends on many factors. Often times the weakest link in the system is the cement mantle that fixes the metal hip stem to the surrounding bone. In an effort to combat this, a hip stem manufacturer came to MSI to develop a better understanding of the effect of their hip stem design on the cement mantle stress distribution and to find ways to improve it.
An offshore rig septuplex pump was experiencing chronic suction and discharge valve failures. A more robust valve design implemented by the manufacturer did not solve the problem. MSI engineers performed test stand and on-rig pulsation and vibration testing.
MSI was tasked with designing a prototype high speed radial gas turbine to operate at 40,000 RPM with R-134a as the working fluid. The goal was to produce 20 HP with a compact turbine and integrated generator unit.
The Civil Engineers at a major Architect/Engineering firm used MSI’s experience and modern methodology to reduce the risk of future schedule- and budget-killing contractor change orders caused by vibration problems.
A manufacturer of cardiovascular stents developed a new design that required FDA approval before it could be sold in the United States. In order to obtain this approval it had to be shown that the stent could withstand the balloon expansion process without developing any cracks.
Mechanical Solutions, Inc. (MSI) was contracted by a power generation company to solve excessive vibration problems on two newly installed Induced Draft (ID) fans. High vibration levels at one times (1x) running speed were reported that exceeded trip levels during start-up. Traditional vibration analysis used by others had not successfully resolved what initially appeared to be a straight-forward unbalance and/or misalignment problem.
A special experimental modal analysis technique, TAP™ (acronym for Time Averaged Pulsing), has been developed by MSI’s engineers. TAP™ can effectively determine critical speeds of all rotating machinery under operating conditions, so that they can be “bump” tested for natural frequencies, without shutting them down.
MSI was contracted by a major South American petrochemical plant to perform detailed vibration tests and FEA modal and stress analysis on a Urea Vibrating Screener. The screener had been suffering periodic failures due to cracks along the welds, plates, and structural beams, as well as hanger wire failures since installation in 1999.
The customer approached MSI during the design phase of their project looking for assistance with improving an existing hydro turbine design for ultra-low head hydropower applications. The design incorporated unique elements not common in the industry, and presented several unique challenges.
A South East Asian power plant was experiencing high vibration and cracking in the exhaust hood of one of its steam turbines. The typical troubleshooting approach is to travel to the site of the machinery, collect the data, analyze it at the home office, and provide a specific solution. However, in order to meet the customer’s timing, technical, and other requirements, MSI agreed to implement a new remote problem solving approach.
MSI was contracted by a major domestic pump manufacturer to determine the torsional natural frequencies of a machinery train consisting of a five plunger reciprocating pump, a gear set including an intermediate shaft, and a VFD/motor driver.
MSI worked closely with a major compressor OEM to specify, install and conduct strain gage testing of a centrifugal compressor impeller on the OEM test stand. MSI utilized its state-of-the-art FM telemetry system to transmit 5 simultaneous channels of data with each channel at either 5 or 10 kHz.
A commercial-off-the-shelf power supply was to be modified for military use. It was not obvious whether the existing design was robust enough to pass the military shock (MIL-S-901D) and vibration (MIL-S-167) test protocols. Before expensive prototypes were manufactured and tested, the system was to be analytically evaluated in an effort to identify weak points so that they could be redesigned.
A Middle East power plant had a serious 1X running speed vibration problem with some vertical turbine pumps (VTP) for service water and associated piping. Although these pumps were not central to the production of power, the plant could not run for extended periods without them, and motor bearing and discharge head mechanical seal problems were causing chronic pump shut-downs.
A nuclear power company purchased several new service water vertical turbine pumps for their power plant. As for all new nuclear installations, it needed to be shown that these pumps could withstand a standardized earthquake loading without structural failure.
MSI was called in by an end-user to help troubleshoot a newly commissioned critical compressor train experiencing unexplained vibration trips. These sudden vibration trips threatened to jeopardize delivery of product and thereby result in a substantial loss of revenue.
In general, MSI’s role in helping to ensure equipment reliability takes place at three levels: (a) preconstruction audits and analysis during the design phase to help prevent problems, (b) using specialized testing and analysis techniques to solve performance, acoustic, vibration, stress, or thermal problems before failure takes place, and (c) performing root cause analysis (RCA) after a failure.
Impact testing was used to determine the reasons for three failures of a hydrocarbon cracking pump which was critical to a diesel fuel production process at a major California refinery. Each failure closed down or severely curtailed fuel production at the refinery, at an average cost of about $3/4 million per day.
MSI was contracted by a major petrochemical company to determine the reasons for chronic lineshaft failures in some 100 foot (30 meter) long vertical pumps, in service on an offshore oil platform. The natural frequencies predicted by the model, and their associated mode shapes, were to be evaluated for possible participation in the failures.
MSI was tasked with evaluating a 1920s Francis style hydro-turbine runner in order to replace the aging original ones at a plant near the Hudson River in Upstate NY. A new blade design improved runner efficiency as well as decreased the blade count from 16 to 15, reducing the runner weight.
A municipality receiving its water supply from a high elevation spring sought to replace an energy wasting pressure reducing valve with a hydro turbine. MSI was tasked with designing the turbine to capture power over a challenging range of operating conditions.
Challenge: Reduce the number of stages required to perform duty for a multistage vertical pump. Results: Impeller modification and de-swirl vane change. Impact: Increased efficiency and head production per stage, reducing the total stages required resulting in significant savings in production.
A new hydropower design was tested by the customer, with actual test stand results significantly lower than the customer’s predicted performance. MSI was tasked with resolving the discrepancy, either by determining the flaw in the testing apparatus/procedure, or by correcting the computer model to better represent actual performance.
Mechanical Solutions, Inc. (MSI) was contracted by a manufacturer to perform a seismic structural analysis on three identical large pump systems in a low-activity and high-activity nuclear waste treatment process. The scope of the analysis included the pressure containment casing, nozzle attachments, support system and driver. The pump systems were required to meet the specs of Seismic Category 1 (SC-1).
Mechanical Solutions, Inc. (MSI) performs pump casing structural analysis typically under contract from pump manufacturers. The starting point includes drawings or solid models, materials of construction information, operating conditions, and a discussion about any unusual concerns or issues.
MSI engineers performed a torsional analysis of a reciprocating pump/gear/motor system being designed for a large overseas petroleum drilling venture. Analysis of the initially designed system indicated that there was a possibility of resonant torsional vibration, driven by 50 Hz line frequency.
Marina Barrage is part of a comprehensive flood control system to eliminate flooding disasters in Singapore. The two-fold responsibility of Mechanical Solutions, Inc. (MSI) was to ensure that: a) the flood control motors, gearboxes, and pumps would not have any life-limiting vibration problems; and b) the pump systems would not cause vibration in the pump house and adjoining visitor’s center including annoying window vibration when the pumps were operational.
Execution of an experimental modal analysis which revealed potential resonance issues on a fin fan oil cooler before commissioning at a petroleum refinery. A finite element analysis helped develop a fix before the unit was ever started.
Mechanical Solutions, Inc. (MSI) provides plant operators and engineering firms with analysis services to validate how new or retrofitted machinery and plant configurations will perform to avoid post-installation issues once the system is installed and operational . This is referred to as a design assessment, and is relatively low-cost "insurance" against potential problems during commissioning or over the life of the machinery system. These same analysis techniques are also applied to understand and characterize problems, and design solutions for issues uncovered after installation or as equipment including support systems age.
In response to the flood damage to New Orleans by Hurricane Katrina, the U.S. Army Corps of Engineers Hurricane Protection Office awarded a design and build contract to a new prime contractor in 2007. The goal was to increase the pumping capacity at the 17th Street and London Avenue canals, allowing for future worst case hurricane drainage to be pumped out of the city and into Lake Pontchartrain.
An area of concern for gas turbine OEM’s and end users is the effect of casing and structural supports on the rotordynamic response of multi-rotor systems. MSI has conducted sophisticated analysis of such problems utilizing the latest technology available in Finite Element Analysis (FEA) and rotordynamics.
Many of the most demanding challenges in turbomachinery system development are related to the prediction of the interacting effect between fluid loads, thermal loads, structural deflection, and the operating points. By providing an integrated framework for turbomachinery analysis, MSI has reduced the time and complexity of the multiphysics analyses.
A vertical solids-handling pump in a sewage plant experienced a classical vibration problem. Whenever the pump was running, the pump, entire pedestal and nearby piping were shaking. The pump bearings had very limited life, and the mechanical seal would chronically leak. The owner claimed that it was a bad pump, and the OEM said that it was an installation problem.
A Northeastern power plant had experienced chronic boiler feed pump failures for eight years, since the unit involved had been switched from base load to modulated load. The longest that the pump had been able to log between major rotor elements overhauls was five months.
When a hydro turbine gearbox failed, MSI was brought in to determine the extent of the damage and provide an engineered solution to get the turbine generating power as quickly as possible.
MSI was contracted by the OEM to perform testing and analysis to determine the root cause of gear tooth failures on an aeroderivative gas turbine power generation drivetrain. The 37 MW gearbox had broken pinion teeth after several thousand operating hours.
A computer circuit board with a high clock speed processor chip was analyzed in an effort to establish the effectiveness of the cooling system. Processor chips can run too hot and their performance can deteriorate as a result. Different geometries for heat sinks and cooling fan locations can be analyzed in order to optimize chip cooling performance.
Four recently installed vertically mounted, variable speed driven non-clog pumps were suffering from high vibration. In one case, the concrete support piers exhibited cracking damage. MSI was contracted to perform specialized field testing and analysis to characterize the problem. Finite Element Analysis (FEA) was used to design an effective solution.
A manufacturer of spinal implant systems had developed a new external-fixation clamping device to the stage that it was ready to undergo required compression-fatigue testing. Shortly before the testing commenced, the company requested that MSI predict through finite element analysis where the system initially would fail, and at what magnitudes of load.
MSI was contracted by a customer to investigate a series of blade cracking problems in a compressor impeller. An FEA model of the impeller was created to perform a natural frequency modal analysis.
MSI was contacted by a large U.S. pump OEM to perform specialized vibration testing of a single-stage centrifugal pump at their main development facility. Destined for a large petroleum refinery, the double-suction pump would be subject to coke formation in vacuum bottoms service.
A major pump OEM called on MSI to help resolve multiple pump driveshaft failures for an ore mining company in East Africa. At the company’s raw water pumping station, two of the three diesel driven vertical turbine pumps had sustained the catastrophic failures monthly.
MSI was contracted by a major aerospace equipment supplier/manufacturer to design and prototype an FAA-approved vacuum generator for use on commercial aircraft. The design would be subject to strict FAA requirements and RTCA environmental conditions/test procedures for airborne equipment.
How many buckets should a Pelton hydro turbine have? That was the question posed by the customer. MSI created a computational fluid dynamics (CFD) model to determine the optimal torque and power output considering two different configurations.
A turbine end-user wanted to optimize the performance of one of his turbines, and submitted the last stage of his steam turbine for analysis and optimization. The stage was analyzed using CFX software which employed real gas properties in order to correctly model the thermodynamic properties of steam.
Challenge: Design a centrifugal compressor for use in blower applications.Results: An efficient compact design.Impact: High efficiency design achieves compression at reduced power.
MSI was contracted to design a down-hole, multi-set external gear hydraulic motor – pump unit. The system had to meet specific requirements to achieve a design to replace the current pitot jet-pump configuration.
A design audit was carried out in an effort to prevent potential premature bladed disk and impeller fatigue failures of three newly installed critical compressor trains. Such a failure would result in a minimum five day pre-mature repair shutdown and cause over $15M (USD) in lost production revenue to the End User.
MSI completed finite element vibration analysis of an automotive company’s proposed VTP installation. Analysis of the originally designed system indicated that there was a strong probability of resonant lateral vibration, in which the first “reed” frequency of the pump/motor/floor as a combined system would be driven by the 1200 RPM running speed.
A newly constructed European nuclear power plant had all of its main feed pumps exhibiting vibration on the bearing housings in excess of the vibration specifications, by up to a factor of three, depending upon operating load. Nearly all of the vibration was at vane passing frequency.
A hydraulic pump was failing in an aircraft critical safety related service, and a thorough performance evaluation was needed. The evaluation involved operating the pump on a test stand at very cold temperatures in an effort to simulate arctic operating conditions. MSI engineers and technicians were responsible for all aspects of the design and construction of the test rig and loop as well as performance of the test and collection of data.
MSI performs laboratory methods of testing fans for certified aerodynamic performance rating. Below are examples and a description of our test facility capabilities.
The longevity of an artificial knee replacement depends on many factors. Although great strides have been made in improving the wear performance of ultra-high-molecular-weight polyethylene (UHMWPE), tibial insert wear is still one of the most important failure mechanisms. To improve the wear characteristics,
MSI was called on behalf of an engineering construction firm building a new power plant in the Southern Hemisphere. The plant was only weeks away from the commissioning deadline, after which hundreds of thousands of US$ per day liquidated damages would be due.
MSI was contracted by a customer to investigate the source of high displacement vibration at the top of an absorber column (220 feet tall and 13 feet diameter) at low frequency and high displacement (6 inches displacement peak-peak). This high vibration caused the following issues:
Mechanical Solutions, Inc. (MSI) was initially contracted to perform specialized testing to quantify the level of flow instability in a Residual Heat Removal (RHR) pump system by the nuclear power plant owner. The task was to perform a CFD analysis of the existing double suction pump inlet, and to make recommendations for improvement with regard to flow-induced vibrations at low volumetric flow rates.
A nuclear power plant experienced chronic excessive sub-synchronous vibrations in their A and C Residual Heat Removal (RHR) pumps. This vibration became particularly large when Pump C operated at low flow rates, while Pump A was not operating. At this condition, vibration of both pumps was substantial, with Pump A (not operating) vibration levels greater than those of the operating Pump C.
A boiler feed pump (BFP) driven off of the main steam turbine via a fluid drive was experiencing high vibration levels leading to frequent replacement of the fluid drive bearings. The plant depended on the single BFP for power production.
MSI was tasked with designing a subscale (1/6th ) axial hydro-turbine utilizing a belt system to drive a generator. The turbine rotor consisted of a CNC machined wheel with teeth machined on the shroud to utilize an industrial belt for transmitting power. A full turbine system from inlet to draft tube was designed and tested in Massachusetts.
Interest is increasing in the abundance of low head and ultra-low head hydropower opportunities. Given the limited power available from a single turbine in these circumstances, MSI was asked to model and analyze the performance of several hydro turbines operating in parallel.
MSI was contracted to understand and help solve a high vibration problem on an aero-derivative gas turbine driven generator. Vibration levels as high as 1.75 in/s peak at 1x HP rotor running speed measured on the HP compressor had been reported at full load.
A 45 MW steam turbine at a waste-to-energy facility in the Northeast underwent a scheduled repair, at which time the turbine bearings were reworked. After this rework, the turbine periodically experienced very high amplitude shaft vibrations.
MSI engineers performed torsional analysis of a reciprocating pump/ gear/ motor system being designed for a large overseas petroleum drilling venture. Analysis of the initially designed system indicated that there was a possibility of resonant torsional vibration, driven by 50 Hz line frequency.
An example demonstrating the impact of the piping in pre-installation natural frequency analysis. In this case, by determining the effect of the suction/discharge piping on the natural frequencies of the currently installed pumps, the importance of including this piping in future FEA analysis predictions for the new pumps could be quantified.
An example demonstrating the impact of the foundation in pre-installation natural frequency analysis. In this case, by determining the effect of the foundation on the natural frequencies of the currently installed pumps, the importance of including the flooring/foundation in future FEA analysis predictions for the new pumps could be quantified.
An example demonstrating the impact of the water level in pre-installation natural frequency analysis. By taking a system-level approach and performing the analysis at both the high water level (HWL) and low water level (LWL) station conditions, MSI was able to predict a potential resonance problem with the 2nd below-ground pump bending mode within the 1x pump RPM range at the LWL condition. The pump manufacturer was then able to make design changes before building the pump to avoid installing potential resonance and vibration issues.
This case study looks at a nagging problem within the pipeline industry - small bore piping resonance, and shows how to solve it with video vibration tools.
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